Abstracts

Rationale: : To evaluate the efficacy of topiramate and zonisamide as secondary prevention medications after the initial resolution of infantile spasms.Infantile spasms is a potentially devastating form of childhood epilepsy with multiple first-line therapies: prednisolone, ACTH, vigabatrin, and surgery. Although modest data support the use of topiramate and zonisamide as second line treatment for infantile spasms, there is no available data involving potential utility for preventing relapse after successful response to first-line therapy.Methods: In this retrospective cohort study, we catalogued consecutive patients with video-EEG confirmed infantile spasms. Among patients who exhibited a complete response to first-line therapies, we catalogued exposure to zonisamide and topiramate, and the incidence of seizure relapse. The hazard ratio of relapse associated with topiramate and zonisamide exposure was ascertained by multivariate Cox proportional hazards regression.Results: 81 consecutive patients with infantile spasms were successfully treated at UCLA with first-line therapies, including prednisolone (n = 12), ACTH (n = 25), vigabatrin (n = 21), and surgery (n = 17). In an effort to prevent relapse, 28 received topiramate and 24 received zonisamide. 41 patients exhibited seizure relapse during a median follow-up of 35.2 months (IQR 17.7–61.3). A reduction in the hazard of seizure relapse was not observed with topiramate and/or zonisamide therapy (HR = 0.74, 95%CI 0.40–1.38). See Figure 1.Conclusions: This study suggests that among patients with infantile spasms who respond to first-line therapies, neither topiramate nor zonisamide are associated with a substantial reduction in the risk of seizure relapse. With our relatively small sample size, we estimate that we were sufficiently powered to detect a hazard ratio of 0.54.The use of topiramate and zonisamide as secondary prevention should be guided by at best modest expectations of efficacy with consideration of the known risks of these therapies.